Cerebral small vessel disease (SVD) is a vascular neurodegenerative disease which is the leading cause of vascular dementia and causes 20% of strokes. 20-30% of those over 80 show signs of the disease as white matter hyperintensities on MRI scans, doubling their risk of stroke and trebling their risk of dementia. Sporadic SVD is thought to be caused by hypertension but 30% of sufferers are normotensive and an alternative hypothesis implicates loss of integrity of the blood brain barrier (BBB). To investigate this, I studied brains from normotensive people with early stage SVD and found reduced capillary endothelial claudin-5 (a BBB tight junction protein), more oligodendrocyte precursor cells (OPCs; the precursors to myelinating oligodendrocytes), and more microglia/macrophages compared to controls. Furthermore, in a relevant rat model of spontaneous SVD, the Stroke Prone Spontaneously Hypertensive Rat (SHRSP; disease model; DM) I found that reduced endothelial claudin-5 was the earliest change, appearing at 3 weeks of age, followed by OPC proliferation, appearing at 4 weeks, and then increased number of microglia/macrophages, appearing at 5 weeks. Importantly, all these changes occurred at a young age (< 5 weeks), before any measurable hypertension. These changes were confirmed in an ex vivo slice culture model (i.e. removing blood flow), ruling out direct damage by leakage of blood components through an impaired BBB and suggesting an inherent endothelial cell dysfunction as the primary cause, with secondary BBB defects. This hypothesis of endothelial dysfunction is supported by increased endothelial cell proliferation in both human SVD tissue and the DM rats, and lower levels of endothelial nitric oxide synthase (eNOS) in brains of DM rats. To study this further I isolated primary brain microvascular endothelial cells (BMECs) from DM and control rats and found that those from DM rats formed less mature tight junctions (less membranous claudin-5) than control BMECs. I also found that conditioned media (CM) from DM BMECs causes OPCs in culture to proliferate more and mature less. This indicates that the endothelial dysfunction is inherent to the endothelial cells, rather than induced by other cell types, and through secreted factors causes OPC changes mirroring what is seen in vivo. Using an antibody array, I identified HSP90α as a candidate secreted factor and showed that it is necessary (by blocking the protein in CM) and sufficient (by adding recombinant HSP90α) to induce the maturation phenotype in OPCs, but not the proliferation phenotype. The idea that endothelial dysfunction causes SVD begs the question of what causes endothelial dysfunction, especially in our inbred DM rat strain. To establish this, I reanalysed sequencing data of the DM and control rats from a previously published study, searching for mutations which lead to truncated proteins in genes expressed in brain endothelial cells. We confirmed the candidate gene Atp11b, a phospholipid flippase, was mutated as predicted. I found that knocking down Atp11b using siRNA in a control endothelial cell line caused endothelial dysfunction and a loss of tight junction maturity, and that CM from these cells causes OPCs to proliferate more and mature less, mirroring what we see in primary DM BMECs and suggesting that Atp11b has a key function in promoting normal endothelial function. Furthermore, I showed that knocking down Atp11b causes cells to secrete increased levels of HSP90α. I propose a mechanism whereby ATP11B regulates the retention of HSP90α within endothelial cells, which in turns regulates eNOS levels and activity, as has been shown previously. In summary, this work shows that there are many pre-symptomatic changes which occur in the brain in the development of SVD in DM rats, and that these are ultimately caused by endothelial dysfunction. As these changes are similar to those found in spontaneous human SVD, I propose that endothelial dysfunction is a key mechanism of human SVD, which may in the future lead to new therapies.

Current methods of determining spinal cord recovery in mice, post-directed injury, are qualitative measures. This is due to the small size and quickness of mice. This thesis presents a design for a gait acquisition and analysis system able to capture the footfalls of a mouse, extract position and timing data, and report quantitative gait metrics to the operator. These metrics can then be used to evaluate the recovery of the mouse. This work presents the design evolution of the system, from initial sensor design concepts through prototyping and testing to the final implementation. The system utilizes a machine vision camera, a well-designed walkway enclosure, and image processing techniques to capture and analyze paw strikes. Quantitative results gained from live animal experiments are presented, and it is shown how the measurements can be used to determine healthy, injured, and recovered gait.

Une étape critique au cours du développement de médicaments est la mesure ou la prédiction des concentrations du médicament dans un tissu cible, qui peuvent ensuite être liées à des mesures de leur efficacité ou leur toxicité. Les concentrations de médicaments ne pouvant être mesurées dans le cerveau humain, ils doivent être simulés ou prédits en utilisant des approches alternatives de modélisation. L'objectif de cette thèse est de développer in silico des approches de prédiction combinant à la fois des données précliniques in vitro et in vivo dans un modèle physiologique structuré, avec une stratégie translationnelle afin de permettre la simulation de concentrations totales et libres des médicaments dans le cerveau humain. Des modèles pharmacocinétiques physiologiques (PBPK) ont été développés dans cette thèse et évalués pour des médicaments de référence déjà sur le marché, et pour un médicament en cours de développement clinique dans l'industrie pharmaceutique. Ces modèles ont été développés à partir de stratégies de type « Bottom-up » sur la base de données in vitro pour la prédiction de la distribution des médicaments dans le cerveau et comparées à des méthodes de type «top-down » en utilisant des données in vivo. Cette thèse est une thèse sur article construite à partir de 5 articles scientifiques qui sont soit publiés soit en cours de soumission. Le premier article est une revue de la littérature publiée dans le Journal de l'AAPS. Cette revue discute les modèles PBPK disponibles actuellement et a permis d’élaborer des hypothèses de travail dans cette thèse afin de proposer des améliorations de ces modèles. Le deuxième article un article de recherche original publié dans Molecular Pharmaceutics. Cet article vise à démontrer l'élaboration d'une approche cohérente de modélisation pharmacocinétique chez le rat qui peut s’adapter en fonction de la quantité et de la qualité des données obtenues in vivo au cours du développement des médicaments. Un arbre de décision a été construit pour faciliter le paramétrage et la structure appropriée du modèle en fonction des données disponibles. Le troisième article est un article de recherche original publié dans Journal of Pharmaceutical Sciences. Cette étude porte sur le développement d'un modèle PBPK pour la prédiction de la pénétration cérébrale des médicaments, dans lequel son transfert à travers la BHE a été traité de façon mécanistique en séparant les paramètres régissant la quantité (perméabilité) à travers la BHE de sa liaison dans le tissu cérébral. Une stratégie de type vitro - vivo en fonction de la perméabilité des médicaments à travers les monocouches cellulaires in vitro a été proposé afin d'extrapoler la composante de transport actif du composé à l’aide de facteurs d’extrapolation (RAF). Deux autres articles sont en cours d’écriture ou soumis. Ces articles viennent compléter les approches de PBPK pour les médicaments du SNC décrites dans les deux autres articles originaux. Une dernière partie de la thèse constitue la discussion qui met très clairement en évidence l'importance du choix d’une approche de modélisation appropriée ou mieux encore la combinaison des approches fondées sur les connaissances physiologiques, les données expérimentales et les applications prévues dans le développement du médicament. L'avantage du paramétrage mécanistique dans ces modèles PBPK est qu’il améliore leur prédictivité et la simulation de différences inter-espèces. Cette thèse a considérablement contribué à démontrer la nécessité d’associer des données in vitro à des données in vivo dans la structuration des modèles PBPK qui se révèlent alors comme des outils précieux pour la prédiction de la pharmacocinétique cérébrale chez l'homme. / A critical step during drug development is the measurement or the prediction of drug concentrations in the target tissue, which can then be linked to measures of drug efficacy or toxicity. Drug concentrations cannot be directly measured in the human brain, and must be simulated or predicted using alternative modeling approaches. The objective of this thesis is to develop in silico approaches to predict BBB penetration of drugs, combining in vitro and in vivo preclinical data in a physiologically structured model, with a translational strategy to allow the simulation of total and free drug concentrations in the human brain. Physiologically based pharmacokinetic (PBPK) models were developed and evaluated for reference molecules already on the market, as well as for a drug currently under clinical development within the pharmaceutical industry. These models were developed based on both ‘bottom-up’ (model parameter values predicted from in vitro data) and ‘top-down’ (model parameters estimated from in vivo data) strategies. This thesis is comprised of 5 scientific papers which are either published or submitted to peer-reviewed journals. The first article is a review of the literature, published in the AAPS journal. This review discusses the currently published PBPK models available for the mechanistic prediction of BBB penetration of drugs, and proposes a strategy for in vitro-in vivo (IVIVE) extrapolation. The second article is an original research article published in Molecular Pharmaceutics. This article aims to show the development of a coherent pharmacokinetic modeling approach in the rat which can be adapted based on the quantity and quality of data obtained in vivo during the development of new drugs. A decision tree was constructed to enable the appropriate parameterization and model structure based on the available data. The third article is an original research article published in Journal of Pharmaceutical Sciences. This article was based on the development of a PBPK model for the mechanistic prediction of BBB penetration of drugs, in which the active and passive components of permeability were considered separately, as well as the intra-brain tissue binding parameters. An in vitro-in vivo strategy was proposed to extrapolate the active transport component using a relative activity factor (RAF) to account for in vitro-in vivo differences in transporter activity and/or abundance. Two additional articles are either submitted or under preparation. These articles extend the PBPK approaches described in the previous two published original research articles. The final part of this thesis consists of a discussion which emphasizes clearly the importance of the appropriate choice of modeling approach, or even better, a combination of approaches based on physiological knowledge, experimental data and knowledge gathered during the course of drug development. The advantage of mechanistic parameterization of PBPK models is the improved ability for inter-species extrapolation for the subsequent simulation of free or total drug concentrations within the human brain. This thesis has considerably contributed to this rapidly evolving field of CNS drug research and development, showing the importance of combining in vitro and in vivo data within a physiologically based model structure, thus providing a valuable tool for the quantitative prediction of the penetration of drugs in the human brain.

La plupart des médicaments développés pour les maladies du SNC n’atteignent pas leur cible en raison des propriétés uniques de la BHE, nécessitant la mise en place de stratégies de délivrance comme l'utilisation d'un processus physiologique, le RMT. Des peptides ciblant le LDLR (exprimé à la BHE et impliqué dans ces processus) ont été développés. Les objectifs de cette thèse ont été de caractériser le trafic intracellulaire et la capacité de transport de différentes formes de ces peptides dans différents modèles in vitro y compris dans un modèle de BHE.Les résultats obtenus dans une lignée cellulaire surexprimant le LDLR tagué GFP par imagerie en fluorescence montrent que les différentes formes de ces peptides lient le LDLR à la membrane plasmique d’où ils sont internalisés et adressés aux lysosomes sans interférer avec l’endocytose des LDL. Ils permettent l’adressage aux lysosomes de petites molécules (fluorochrome) et de protéines qui leur sont fusionnées, ces résultats indiquent qu’ils pourraient être utilisés pour cibler des molécules thérapeutiques aux lysosomes de cellules exprimant les LDLR. Dans le modèle in vitro de BHE, les peptides sont internalisés via le LDLR à partir du pôle apical et suivent un transport intracellulaire similaire aux LDL, étant déroutés de la voie de dégradation vers les lysosomes pour être transportés jusqu’au compartiment abluminal comme précédemment décrit pour le LDL et la transferrine. Ces données indiquent donc que les peptides ciblant le LDLR sont des candidats vecteurs intéressants pour compléter/améliorer le panel de peptide/anticorps existant et permettre le ciblage et le transport de molécules thérapeutiques à travers la BHE. / Many drugs are ineffective in treating CNS diseases due in part to unique properties of the BBB, requiring the establishment of delivery strategies such as the use of a physiological process, as the RMT. Peptides targeting the LDLR (expressed in the BBB and involved in these processes) have been developed. The objectives of this thesis were to characterize the intracellular traffic and transport capacity of different shapes of these peptides in various in vitro models including a model of BBB.The results obtained in a cell line overexpressing the LDLR tagged GFP by fluorescence imaging shows that the various forms of these peptides bind plasma membrane LDLR, where they are internalized and sent to lysosomes without interfering with LDL endocytosis. They allow lysosomal targeting of small molecules (fluorochrome) and proteins that are fused to them. These results indicate that it might be used to target therapeutic compounds to cells expressing LDLR lysosomes. In the in vitro BBB model, the peptides are internalized via the LDLR from the apical pole and follow a similar intracellular transport than LDL, being diverted from the lysosomal degradation pathway to be transported to the abluminal compartment as previously described for LDL and transferrin. These data indicate that the LDLR-targeting peptides seems useful vectors candidates to complete/improve the existing peptide/antibodies panel and allow the targeting and the transport of therapeutic molecules through the BBB.

La maladie d’Alzheimer (MA) est la maladie neurodégénérative la plus commune et reste à ce jour incurable. Elle se caractérise par l’accumulation dans le cerveau du peptide neurotoxique bêta-amyloïde (Aβ), par une neuroinflammation et des atteintes neurovasculaires, qui ensemble induisent la mort des neurones et des déficits cognitifs. En raison de leurs activités multiples, les métalloprotéases matricielles (MMPs) émergent comme des acteurs importants dans la MA. Mes travaux ont permis de mieux comprendre l’implication de 3 de ces MMPs dans la MA et soulignent le caractère spécifique et complémentaire de MT1- et MT5-MMP, directement impliquées dans la production d’Aβ, et le rôle de MMP-12 dans la neuroinflammation et dans la perte d’intégrité de la barrière hémato-encéphalique, un système vasculaire particulier qui protège efficacement le cerveau. Mes travaux ouvrent des perspectives dans le développement de nouvelles stratégies thérapeutiques basées sur la modulation de ces MMPs. / Alzheimer's disease (AD) is the most common neurodegenerative disease and remains to this day incurable. It is characterized by the accumulation in the brain of the beta-amyloid (Aß) neurotoxic peptide, by neuroinflammation and neurovascular damage, which together induce neuronal death and cognitive deficits. Because of their multiple activities, matrix metalloproteinases (MMPs) are emerging as important players in AD. My work has provided insight into the involvement of 3 of these MMPs in AD and highlight the specific and complementary nature of MT1- and MT5-MMP, directly involved in the production of Aß, and the role of MMP-12 in neuroinflammation and in the loss of integrity of the blood-brain barrier, a particular vascular system, which effectively protects the brain. My work opens perspectives in the development of new therapeutic strategies based on the modulation of these MMPs.

Background The Breast Cancer Resistance Protein (BCRP) drug transporter is important for drug disposition and plays a critical role in regulating drug entry into the brain. Its substrate spectrum overlaps with substrates of Multi Drug Resistance Protein 1 (MDR1, P-gp), which influences and complicates the interpretation of data on drug distribution into tissues (e.g. brain). Distinguishing BCRP mediated transport from the transport by the MDR1 is often problematic. However, with new in vitro tools, this is now possible. In this project, two drug compounds, i.e. Dantrolene and Ritonavir, were investigated using these new in vitro models. The results from the experimental in vitro assay were matched with molecular dynamics (MD) simulations. Using coarse-grained (CG) simulations, a model of the BCRP transporter in a lipid bilayer was built, this model is based on the human BCRP structure revealed by Taylor et al (2017). Simulations were run for Dantrolene (a known substrate of BCRP) independently three times, and another with Ritonavir (a non-substrate) three times. Aim To determine substrate specificity for the BCRP transporter for two compounds, and to construct a CG model of BCRP transporter to see whether in silico methods can be used as an alternative for assessing substrate specificity.  Methods Madin-Darby canine kidney (MDCK) II cell line with no endogenous canine MDR1 (cMDR1) expression (MDCKcMDR1-KO), overexpressing human MDR1 (hMDR1) (MDCK-hMDR1cMDR1-KO) and stable expression of human BCRP (hBCRP) (MDCK-hBCRPcMDR1-KO) cells were cultured and used in Transwell experiments. Samples were analyzed using LC-MS/MS to determine the substrate concentrations. Apparent permeability and efflux ratio was calculated and evaluated.  MD simulations used the Martini 3 CG force field, and were run with Gromacs (version 2020.4). Tools including MODELLER, INSANE and others were used to construct the initial model (Webster, 2000; Wassenaar et al., 2015), for parameterization of substrate and non-substrate molecules. And visual inspection was done with the visual molecular dynamics (VMD) program and PyMOL. Results In vitro transport experiment confirmed that Dantrolene is a BCRP specific substrate, and Ritonavir is MDR1 specific substrate. Following simulations of these two compounds, Dantrolene is observed to stay in the transmembrane domains (TMD) for a certain period (on average several hundreds of nanoseconds), while Ritonavir is not found to bind in the TMD, which provides a proof of concept for future studies.

No description available.

O presente estudo é focalizado na avaliação dos achados do sistema nervoso central através de imagens obtidas através de ressonância nuclear magnética (RNM) em pacientes com a Síndrome de Opitz G/BBB. A síndrome de Opitz G/BBB (OMIM; 145410; 300000) é uma síndrome de anomalias congênitas múltiplas que comprometem a linha média, clinica e geneticamente heterogênea, com uma forma ligada ao cromossomo X mapeada em Xp22.3 e uma outra forma supostamente autossômica dominante mapeada em 22q11 cujo gene nunca foi identificado; no entanto, ambas são reconhecidas como uma condição única. Esta síndrome de anomalias da linha média se caracteriza principalmente por hipertelorismo, bico de viúva, ponte nasal larga, hipospádia, fissura de lábio/palato, e anomalias laringo-traqueo-esofágicas. Neste estudo avaliamos 19 pacientes do sexo masculino, brasileiros, sem etnia específica, com idades variando entre 5 e 38 anos, diagnosticados previamente como portadores de síndrome de Opitz G/BBB, selecionados dos arquivos da Seção de Genética Clinica, Divisão de Sindromologia, HRAC-USP Bauru. Destes pacientes, 6 tinham avaliação prévia por estudos de genética molecular gentilmente realizados pelas Dras. Chiara Migliore (Institute for Maternal and Child Health - IRCCS \"Burlo Garofolo\", Trieste, Italy) e Germana Meroni (CBM - Cluster in Biomedicine, AREA Science Park, Trieste, Italy). Os estudos por imagem através de RNM foram realizados em todos os pacientes. Atenção especial foi dedicada a 3 pacientes que mostravam fenótipos clínicos distintos dos demais dentro do espectro da síndrome de Opitz G/BBB: dois pacientes apresentavam ptose, pescoço alado, e anomalias da cintura escapular, enquanto que o terceiro apresentava retardo mental grave e microcefalia associado a graves alterações encefálicas na avaliação por imagem, tais como atrofia cortical generalizada e grande anomalia de Dandy-Walker. Os principais achados por imagem da amostra total são representados por cisterna magna ampla (15 indivíduos = 78,95%), dilatação do 4º ventrículo (14 = 73,68%), hipoplasia do vermis cerebelar (8 = 42,10%), hemisférios cerebelares anômalos e cavum septum vergae (3 = 15,79% cada condição); atrofia de córtex cerebral, alargamento do III ventrículo, aumento da cisterna pré-pontina, hipoplasia de corpo caloso e persistência de septo pelúcido contam, cada um, com dois pacientes acometidos (10,53%). Aparentemente não havia correlação entre o fenótipo clínico e os achados por imagem, existindo grande variabilidade de paciente para paciente, que se estendiam desde discretas alterações da linha média até grave malformação de Dandy-Walker. As alterações comportamentais e cognitivas usualmente descritas na literatura como achados principais em pacientes com hipoplasia do vermis cerebelar e/ou hipoplasia cerebelar não foram reconhecidas como achados marcantes nos pacientes do presente trabalho. A alta frequência de anomalias cerebelares em pacientes com a síndrome de Opitz G/BBB nos leva a recomendação para a reformulação do aconselhamento genético, abordagem e manejo destes pacientes. / The present survey focused on the evaluation of the central nervous system images findings in patients with the Opitz G/BBB syndrome obtained through magnetic nuclear resonance imaging (MRI). The Opitz G/BBB syndrome (OMIM; 145410; 300000) is a midline congenital malformation syndrome, clinical and genetically heterogeneous with an X-linked form mapped on Xp22.3 and a not well defined autosomal dominant form purportedly on 22q11, however they are recognized as one entity. This multiple congenital midline malformation syndrome is mainly characterized by hypertelorism, widows peak, broad nasal bridge, hypospadias, cleft lip/palate, and laryngo-tracheo-esophageal abnormalities. In the present study we have evaluated nineteen male patients of Brazilian extraction, with no preferential ethnic background, with age span ranging from 5 to 38 years old and previously diagnosed with the OS were selected from the files of the Section of Clinical Genetics, Division of Syndromology, HRAC-USP Bauru. From these patients, six had previous evaluation through molecular analysis graciously performed by Chiara Migliore (Institute for Maternal and Child Health - IRCCS \"Burlo Garofolo\", Trieste, Italy) and Germana Meroni (CBM - Cluster in Biomedicine, AREA Science Park, Trieste, Italy). Imaging studies through MRI were performed in all patients. Special attention was given to 3 out the 19 patients who showed unique phenotypes within the OS spectrum: 2 of them presented ptosis, pterigium colli, and abnormal scapular girdle as deviant signs and they presented mild/moderate cerebellar anomalies, and the 3rd presented severe mental retardation and microcephaly associated to generalized severe imaging findings mainly represented by generalized cortical atrophy and huge Dandy-Walker anomaly. Main MRI findings of the whole sample included wide cisterna magna (15 = 78,95%), enlarged 4th ventricle (14 = 73,68%), cerebellar vermis hypoplasia (8 = 42,10%); abnormal cerebellar hemispheres and cavum septum vergae (3 = 15,79% each one); cerebral cortical atrophy, enlarged III ventricle, enlarged prepontine cisterna, calosal hypoplasia and cavum septum pellucidum counts, each one, two patients (10,53%). Apparently there is no correlation between the clinical phenotype and the imaging findings, and there is a wide variability from patients to patients, ranging from mild midline anomalies to severe Dandy Walker anomaly. Behavioral and severe cognitive deficits usually reported in the pertinent literature as main findings associated to cerebellar vermis hypoplasia and/or cerebellar hypoplasia were not recognized as a remarkable finding in the present series. The high frequency of cerebellar anomalies in the OS patients led us to recommend a reformulation in the genetic counseling approach to these patients.

Malignant brain tumor is one of the most lethal forms of cancers. In the United States alone, approximately 20,500 new cases of primary malignant brain and central nervous system tumors are expected to be diagnosed in 2007 with 12,740 deaths estimated. Treatment of malignant brain tumor remains a major challenge despite recent advance in surgery and other adjuvant therapies, such as chemotherapy. The failure of potential effective chemotherapeutics for brain tumor treatment is usually not due to the lack of potency of the drug, but rather can be attributed to lack of therapeutic strategies capable of overcoming blood brain barrier for effective delivery of drug to the brain tumor. In this thesis, we developed a minimally invasive sustained release system for glioma therapy. The present study was initiated in an effort to incorporated Doxorubicin (DOX) loaded PLGA particle into an agarose gel, which can provide a continuous release of DOX locally to the tumor site. DOX, a toposiomearase II inhibitor, is not currently used clinically for brain tumor treatment because when delivered systemically it does not cross BBB. Our hydrogel particle system can overcome this shortcoming of DOX. The results from this study demonstrate that the DOX/PLGA particle gel system can maintain the bioactivity of DOX and sustained release DOX for at least 15 day in vitro. The result of in vivo study showed the DOX/PLGA particle gel treated group had significantly extend the medium survival of 9L glioma bearing rat from 21 days to 29 days. Therefore, the success experience of this local and sustained delivery device might benefit the development of future glioma therapy strategy.

O presente estudo é focalizado na avaliação dos achados do sistema nervoso central através de imagens obtidas através de ressonância nuclear magnética (RNM) em pacientes com a Síndrome de Opitz G/BBB. A síndrome de Opitz G/BBB (OMIM; 145410; 300000) é uma síndrome de anomalias congênitas múltiplas que comprometem a linha média, clinica e geneticamente heterogênea, com uma forma ligada ao cromossomo X mapeada em Xp22.3 e uma outra forma supostamente autossômica dominante mapeada em 22q11 cujo gene nunca foi identificado; no entanto, ambas são reconhecidas como uma condição única. Esta síndrome de anomalias da linha média se caracteriza principalmente por hipertelorismo, bico de viúva, ponte nasal larga, hipospádia, fissura de lábio/palato, e anomalias laringo-traqueo-esofágicas. Neste estudo avaliamos 19 pacientes do sexo masculino, brasileiros, sem etnia específica, com idades variando entre 5 e 38 anos, diagnosticados previamente como portadores de síndrome de Opitz G/BBB, selecionados dos arquivos da Seção de Genética Clinica, Divisão de Sindromologia, HRAC-USP Bauru. Destes pacientes, 6 tinham avaliação prévia por estudos de genética molecular gentilmente realizados pelas Dras. Chiara Migliore (Institute for Maternal and Child Health - IRCCS \"Burlo Garofolo\", Trieste, Italy) e Germana Meroni (CBM - Cluster in Biomedicine, AREA Science Park, Trieste, Italy). Os estudos por imagem através de RNM foram realizados em todos os pacientes. Atenção especial foi dedicada a 3 pacientes que mostravam fenótipos clínicos distintos dos demais dentro do espectro da síndrome de Opitz G/BBB: dois pacientes apresentavam ptose, pescoço alado, e anomalias da cintura escapular, enquanto que o terceiro apresentava retardo mental grave e microcefalia associado a graves alterações encefálicas na avaliação por imagem, tais como atrofia cortical generalizada e grande anomalia de Dandy-Walker. Os principais achados por imagem da amostra total são representados por cisterna magna ampla (15 indivíduos = 78,95%), dilatação do 4º ventrículo (14 = 73,68%), hipoplasia do vermis cerebelar (8 = 42,10%), hemisférios cerebelares anômalos e cavum septum vergae (3 = 15,79% cada condição); atrofia de córtex cerebral, alargamento do III ventrículo, aumento da cisterna pré-pontina, hipoplasia de corpo caloso e persistência de septo pelúcido contam, cada um, com dois pacientes acometidos (10,53%). Aparentemente não havia correlação entre o fenótipo clínico e os achados por imagem, existindo grande variabilidade de paciente para paciente, que se estendiam desde discretas alterações da linha média até grave malformação de Dandy-Walker. As alterações comportamentais e cognitivas usualmente descritas na literatura como achados principais em pacientes com hipoplasia do vermis cerebelar e/ou hipoplasia cerebelar não foram reconhecidas como achados marcantes nos pacientes do presente trabalho. A alta frequência de anomalias cerebelares em pacientes com a síndrome de Opitz G/BBB nos leva a recomendação para a reformulação do aconselhamento genético, abordagem e manejo destes pacientes. / The present survey focused on the evaluation of the central nervous system images findings in patients with the Opitz G/BBB syndrome obtained through magnetic nuclear resonance imaging (MRI). The Opitz G/BBB syndrome (OMIM; 145410; 300000) is a midline congenital malformation syndrome, clinical and genetically heterogeneous with an X-linked form mapped on Xp22.3 and a not well defined autosomal dominant form purportedly on 22q11, however they are recognized as one entity. This multiple congenital midline malformation syndrome is mainly characterized by hypertelorism, widows peak, broad nasal bridge, hypospadias, cleft lip/palate, and laryngo-tracheo-esophageal abnormalities. In the present study we have evaluated nineteen male patients of Brazilian extraction, with no preferential ethnic background, with age span ranging from 5 to 38 years old and previously diagnosed with the OS were selected from the files of the Section of Clinical Genetics, Division of Syndromology, HRAC-USP Bauru. From these patients, six had previous evaluation through molecular analysis graciously performed by Chiara Migliore (Institute for Maternal and Child Health - IRCCS \"Burlo Garofolo\", Trieste, Italy) and Germana Meroni (CBM - Cluster in Biomedicine, AREA Science Park, Trieste, Italy). Imaging studies through MRI were performed in all patients. Special attention was given to 3 out the 19 patients who showed unique phenotypes within the OS spectrum: 2 of them presented ptosis, pterigium colli, and abnormal scapular girdle as deviant signs and they presented mild/moderate cerebellar anomalies, and the 3rd presented severe mental retardation and microcephaly associated to generalized severe imaging findings mainly represented by generalized cortical atrophy and huge Dandy-Walker anomaly. Main MRI findings of the whole sample included wide cisterna magna (15 = 78,95%), enlarged 4th ventricle (14 = 73,68%), cerebellar vermis hypoplasia (8 = 42,10%); abnormal cerebellar hemispheres and cavum septum vergae (3 = 15,79% each one); cerebral cortical atrophy, enlarged III ventricle, enlarged prepontine cisterna, calosal hypoplasia and cavum septum pellucidum counts, each one, two patients (10,53%). Apparently there is no correlation between the clinical phenotype and the imaging findings, and there is a wide variability from patients to patients, ranging from mild midline anomalies to severe Dandy Walker anomaly. Behavioral and severe cognitive deficits usually reported in the pertinent literature as main findings associated to cerebellar vermis hypoplasia and/or cerebellar hypoplasia were not recognized as a remarkable finding in the present series. The high frequency of cerebellar anomalies in the OS patients led us to recommend a reformulation in the genetic counseling approach to these patients.